With rapid development of display technology, touch-screen panels have been gradually applied in many aspects of people's life. At present, touch-screen panels, according to their working principles, can be classified as: resistive, capacitive, infrared, and surface acoustic wave types. Among them, capacitive touch-screen panels, by virtue of their unique touch principles and their advantages of high sensitivity, long life and high light transmittance, etc., become the most favorable and pursued products in the industry.
At present, a capacitive in-cell touch-screen panel can be achieved by additionally incorporating touch scanning lines and touch sensing lines directly on a TFT (Thin Film Transistor) array substrate; that is, on the surface of a TFT array substrate, two layers of strip-like ITO (Indium Tin Oxide) electrodes, which are on different levels and intersect with each other, are manufactured, and these two layers of ITO electrodes are used as touch scanning lines and touch sensing lines of the touch-screen panel, respectively; meanwhile, an inductive capacitor is formed at the non-coplanar intersection between the two ITO electrodes. The working process of the above-described in-cell touch-screen panels is: when touch scan signals are loaded to an ITO electrode acting as a touch scanning line, the coupled voltage signals obtained by a touch sensing line via an inductive capacitor are detected, and during this process, when a human body contacts the touch-screen panel, the human body electric field will act on the inductive capacitor, which causes the capacitance of the inductive capacitor to change, and further causes the coupled voltage signals obtained by the touch sensing line to change; then, according to the changes of the voltage signals, the position of the touch-point can be determined.
An aperture ratio refers to a proportion of the light transmission area of each pixel without the area of wirings and transistor (usually shielded by a black matrix) to the total area of this pixel. The higher the aperture ratio, the higher the efficiency of light transmission is. The above-described capacitive in-cell touch-screen panel will reduce the aperture ratio of the TFT substrate, and further affect the light transmittance of the TFT array substrate because additional touch scanning lines and touch sensing lines as well as driver circuits are needed on a TFT array substrate.
Moreover, in the above-described capacitive in-cell touch-screen panel, the added two layers of ITO electrodes will overlap with the existing data lines and gate lines in a TFT array substrate in a vertical direction, and therefore the ITO electrodes, when transmitting touch scan signals, will cause severe signal-interference with the primary display drive signals in the TFT array substrate, which will probably result in maloperation of the TFT array substrate.